Alternator question
They are external reg.
Operation
The threaded post is the battery connection
The two pin plug in back of the alt allows the PCM to govern when the regulator goes into "charge" mode.
Wiring
Can't help you on where the two pin plug wire goes fro the back of the alt.....maybe one goes to "field" and the other to the PCM?
...or maybe both go to the reg?